Traffic should flow best in cities when only a limited number of roads lead to the centre. This counter-intuitive finding could allow planners to prevent gridlock by closing roads rather than building new ones.

It comes from a new way of thinking about complex networks developed by Neil Johnson, Douglas Ashton and Timothy Jarrett at the University of Oxford, UK.

Fascinatingly, the article goes on to say:

The same process of analysing the costs associated with moving across a network could help solve a long-standing problem in biology: why some natural networks are centralised like cities, whereas others are decentralised like the internet.

“Organisms such as fungi have managed to evolve a complex network in which there are centralised and decentralised pathways to move nutrients around,” Johnson says. “Now we can look at biological systems in terms of the ‘costs’ and ‘benefits’ of the connections rather than in terms of the physical structures themselves,” he says.